3-DIMENSIONAL INITIAL DATA FOR THE COLLISION OF 2 BLACK-HOLES .2. QUASI-CIRCULAR ORBITS FOR EQUAL-MASS BLACK-HOLES

The construction of initial-data sets representing binary black-hole c onfigurations in quasicircular orbits is studied in the context of the conformal-imaging formalism. An effective-potential approach for loca ting quasicircular orbits is outlined for the general case of two hole s of arbitrary size and with arbitrary spins. Such orbits are explicit ly determined for the case of two equal-sized nonrotating holes, and t he innermost stable quasicircular orbit is located. The characteristic s:of this innermost orbit are compared to previous estimates for it, a nd the entire sequence of quasicircular orbits is compared to results from the post-Newtonian approximation. Some aspects of the numerical e volution of such data sets are explored.